Calcium/calmodulin-dependent protein kinase II (CaM kinase) has been implicated in synaptic plasticity in both vertebrates and invertebrates and has properties which suggest that it may be a "molecular switch". Studies in Drosophila melanogaster and in mice have shown that CaM kinase is required for learning and memory. The objectives of the proposed study are threefold: 1) Identification of proteins that interact with CaM kinase. Using the yeast two-hybrid system, we will identify and characterize substrates, regulators and localizers of CaM kinase that are involved in neuronal function. The in vivo phosphorylation of Eag, a potassium channel subunit, will be studied. 2) Identification of genes that interact with CaM kinase. Mutations at the CaMK locus are lethal in the homozygous state, but viable as CaMK/+ heterozygotes. We will perform an enhancer screen to identify genes which, when mutant, enhance lethality of CaMK/+ heterozygotes. 3) Characterization of the larval NMJ phenotype of CaML/+ flies. We will assess the effects on identified ionic currents and neuronal plasticity at the NMJ in mutants lacking one copy of the CaMK gene. 4) Characterization of the membrance properties of CNS neurons which require CaM kinase for plastic behavior. We will study cultured CNS cells that have been shown to be involved in CaM kinase-dependent courtship conditioning. We will assess the effects of CaM kinase on identified currents in these cells. Cognitive functions such as learning and memory are impaired in many disease states. Understanding the biochemical basis of normal changes in neuronal properties is an important first step in understanding how pathological processes can disrupt brain function. The ability to genetically manipulate CaM kinase in DrosophiLa will allow us to understand not only its biochemical role, but its role in cellular and behavioral processes. The funding of this proposal would significantly enhance the ability of the PI to accomplish these goals by reducing her teaching and administrative duties. The interdisciplinary nature of this research program necessitates central involvement of the PI in training of students and postdocs in techniques and areas in which they are inexperienced. The PI will also be involved with the integration of electrophysiology into the research program as a new tool for studying the roles of CaM kinasein neuronal function.